CONTRIBUTIONS TO PALEONTOLOGY. 165 



A movable cheek ( Plate tH, f. 41), occurring in the same association 

 (and with scarcely any fragments of other fossils), I have referred to this 

 species with doubt. 



There is also a pygidinm in the same specimens, which I have referred 

 to this species. It is more than twice as wide as long ; the axis is conical, 

 abruptly elevated, and marked by six annulations besides the anterior ar- 

 ticulating joint. The sides are nearly flat, and marked by four ribs which 

 are flattened and faintly grooved. 



Dr. Shumard has very kindly sent me a specimen of the species described 

 by him as DiMocephalus latifrons, consisting of the large frontal limb and 

 the principal part of the glabella ( Plate vii, fig. 40). On comparison with 

 seven or eight individuals of the species which I have identified with Crepi- 

 cejjhalus? ivisconsensis of Owen, I can find no characters which separate 

 the two. From its conical glabella and oblique furrows, I place it with 

 CoNOCEPHALiTES. It is clearly related generically to Lonchocephalus 

 ( ConocephalitesJ hamulus of Owen. 



The great width of frontal limb shown in Dr. Owen's figure of Crepi- 

 cephalus luisconsensis is a character not possessed in an equal degree by 

 any other species except Conocephalites hamulus, and, approximately, by 

 Conocephalites diadematus. The contour of the limb in the two last is dif- 

 ferent from that of the figure of Dr; OwEN, which corresponds with the 

 specimens I have referred to that species. In the figure cited ( Tab. I, f. 13), 

 the frontal limb is equal in length to the width of the glabella near the 

 front ; a feature which corresponds with the specimens I have figured, and 

 with others of the same species. In the specimen of Dr. Shumard, the 

 length of the frontal limb is proportionally a little greater ; but I do not 

 regard this difference as of specific importance. 



PLATE VII. 



Fig. 39. The glabella and fixed cheeks of a small individual. 



Fio. 40. The frontal limb and part of the glabella of a large individual, showing ra- 

 diating striae on the frontal limb. This figure is from Dr. Shumard's specimen. 



Fig. 41. A cheek (associated with the glabella at Trempaleau), showing the direction 

 of the facial suture in its posterior extension. 



PLATE VIII. 

 Fig. 22. The glabella, preserving part of the fixed cheeks, frontal limb, and posterior 

 spine. 



Fig. 23. Profile of the same. 



Fig. 24. Pj-gidium associated in the stone with the specimen fig. 22, and several other 

 similar ones. 



Fig. 27. A smaller specimen, presenting some slight variations from the preceding 



figure 22. 

 Fig. 28. Profile of the same. 



This species occurs at Trempaleau, Wisconsin, and opposite the mouth of 

 the Chippewa river in Minnesota, associated with Ftychaspis granulosa, 

 Agnostus josepha, etc., in beds that I have recognized as the second fossili- 

 ferous group of the sandstone. The locality of Dr. Owen's specimen is not 

 given ; but from its association with Ftychaspis ( Dikelocephalus) granu' 

 losus, I infer it to have been from near Trempaleau. 



